Antennas are used to typically radiate and/or receive electromagnetic signals, preferably with antenna gain, directivity, and efficiency. Practical antenna design traditionally involves trade-offs between various parameters, including antenna gain, size, efficiency, and bandwidth.
Antenna design has historically been dominated by Euclidean geometry. In such designs, the closed area of the antenna is directly proportional to the antenna perimeter. For example, if one doubles the length of an Euclidean square (or “quad”) antenna, the enclosed area of the antenna quadruples. Classical antenna design has dealt with planes, circles, triangles, squares, ellipses, rectangles, hemispheres, paraboloids, and the like.
With respect to antennas, prior art design philosophy has been to pick a Euclidean geometric construction, e.g., a quad, and to explore its radiation characteristics, especially with emphasis on frequency resonance and power patterns. Unfortunately antenna design has concentrated on the ease of antenna construction, rather than on the underlying electromagnetics, which can cause a reduction in antenna performance.
Practical antenna design traditionally involves trade-offs between various parameters, including antenna gain, size, efficiency, and bandwidth. Antenna size is also traded off during antenna design that typically reduces frequency bandwidth. Being held to particular size constraints, the bandwidth performance for antenna designs such as discone and bicone antennas is sacrificed resulted in reduced bandwidth.
In general, a wideband requirement for an antenna, especially a dipole-like antenna, has required a bicone or discone shape to afford the performance desired over a large pass band. For example, some pass bands desired exceed 3:1 as a ratio of lowest to highest frequencies of operation, and typically ratios of 20:1 to 100:1 are desired. Referring to FIG. 1, prior art discone antenna 5 includes a sub-element 10 shaped as a cone whose apex is attached to one side of a feed system at location 20. A second sub-element 30 is attached to the other side of the feed system, such as the braid of a coaxial feed system. This sub-element is a flat disk meant to act as a counterpoise.
Referring to FIG. 2, another current antenna design is depicted that includes a bicone antenna 35, in which a sub-element 40 is arranged similar to sub-element 10 shown the discone antenna 5 of FIG. 1 with a similar feed arrangement at location 50. However, for bicone antenna 35 rather than a second sub-element shaped as a disk, a second cone 60 is attached.
While certain embodiments are shown in the drawings, one skilled in the art will appreciate that the embodiments depicted in the drawings are illustrative and that variations of those shown, as well as other embodiments described herein, may be envisioned and practiced within the scope of the present disclosure.